From b5962c6b50f65f56b1b83bbdce56cece72e4048c Mon Sep 17 00:00:00 2001
From: Mwa <mwa@mwaaa.fr>
Date: Fri, 20 Mar 2026 11:18:48 +0100
Subject: [PATCH] minor performance improvement for jump/call

---
 simu/src/cpu.rs | 19 ++++++++-----------
 1 file changed, 8 insertions(+), 11 deletions(-)

diff --git a/simu/src/cpu.rs b/simu/src/cpu.rs
index 9fd92ed..410f2fb 100644
--- a/simu/src/cpu.rs
+++ b/simu/src/cpu.rs
@@ -163,7 +163,6 @@ impl TryFrom<u32> for Instruction {
         Ok(match value >> 30 {
             0b00 => {
                 let t = value & (1 << 29); // 3rd bit set
-                let value = value - t;
                 let t = t != 0;
                 if t {
                     Self::Call(value)
@@ -589,10 +588,8 @@ impl Computer {
                                 self.pc += d as usize
                             }
                         }
-                        Instruction::Jump(mut addr) => {
-                            if addr & (1 << 28) != 0 {
-                                addr += 7 << 29;
-                            } else if addr == 0 {
+                        Instruction::Jump(addr) => {
+                            if unlikely(addr == 0) {
                                 #[cfg(feature = "debug")]
                                 {
                                     match self.interupts {
@@ -616,15 +613,14 @@ impl Computer {
                                 }
                                 SHARED.external_interupts.wait(0);
                             }
-                            self.pc = (addr + self.pc as u32) as usize;
+                            self.pc = ((addr + self.pc as u32) & 0x1FFF_FFFF) as usize;
                         }
-                        Instruction::Call(mut addr) => {
+                        Instruction::Call(addr) => {
+                            //WARNING! addr still has the type bit set at this point!
                             self.sp -= 1;
                             self.ram[self.sp] = ((self.pc << 2) + 4) as u32;
 
-                            if addr & (1 << 28) != 0 {
-                                addr += 7 << 29;
-                            } else if unlikely(addr == 0) {
+                            if unlikely(addr == 0 + (1 << 29) /*t bit*/) {
                                 #[cfg(feature = "debug")]
                                 {
                                     println!("program terminated");
@@ -634,7 +630,8 @@ impl Computer {
                                 #[cfg(not(feature = "debug"))]
                                 exit(0);
                             }
-                            self.pc = (addr + self.pc as u32) as usize;
+                            //The mask take care of both wrapping and shedding the t bit
+                            self.pc = ((addr + self.pc as u32) & 0x1FFF_FFFF) as usize;
                         }
                         Instruction::Ret() => {
                             self.pc = (self.ram[self.sp] >> 2) as usize;